It is increasingly common for flexible pipes and hoses to be used to convey fluids. When an operation such as a repair or a modification, such as the addition of a branch line, is to be performed on a flexible hose or pipe it may not be convenient or feasible to close a permanently installed valve to shut down the flow through the pipe where the repair or other work operation is to be performed. In those instances it is common practice to use a temporary clamping device to flatten the pipe so as to close it to the flow of liquid and allow the work operation to be performed. When the work is completed the clamping device is released to again open the pipe and allow fluid flow to resume. It is important in performing the clamping operation to avoid damage to the pipe, because such damage creates a weak spot in the pipe and increases the likelihood that leaks and other failures will immediately or subsequently develop
Devices for temporarily clamping pipes are known in the prior art, but the prior art devices have certain inherent disadvantages and none of them has proved to be completely satisfactory. In one approach two straight members are hinged together at one end, so that the members can be positioned on either side of a pipe, squeezed together to bring them toward parallel orientation so as to flatten the pipe, and then fastened at their free ends by various means. In this design the two members are not brought into completely parallel orientation unless the inner surfaces of the two members are directly in contact with each other. When a pipe is compressed between the two members during use of the device the thickness of the pipe wall prevents the device from being fully closed, and they remain disposed at an angle relative to each other. As a result, the space between them adjacent to the hinge is less than the space between them near their outer ends, and the pipe is not uniformly compressed. When sufficient force is applied to fully close the pipe to fluid flow the portion of the pipe wall nearest the hinge of the device is often excessively compressed and damaged. In some prior art devices the length of the hinged members is increased, to gain additional leverage for compressing the pipe, and also to allow the pipe to be positioned near the free ends of the members to minimize the difference in wall compression across the pipe. However, the additional length can make such devices difficult to use in a confined space, such as a trench, without additional excavation.